this post was submitted on 09 Jan 2025
196 points (100.0% liked)

interestingasfuck

6150 readers
365 users here now

interestingasfuck

founded 2 years ago
 

The shiny puddles look like some low-temp metal melted and oozed out of the car as it burned. I wonder what part(s) melted, and what type of metal it is?

The picture is from a NPR piece about the current Los Angeles wildfires: https://www.npr.org/sections/the-picture-show/2025/01/09/g-s1-41784/los-angeles-fire-photos

all 26 comments
sorted by: hot top controversial new old
[–] Tehdastehdas@lemmy.world 6 points 7 hours ago

Were the front wheels made from two metals of different melting points?

[–] Kolanaki@yiffit.net 16 points 10 hours ago (2 children)

I'm guessing it's aluminium. Looks the same as what would be left over after a bonfire with my friends (we'd toss empty beer cans into it).

[–] Tangent5280@lemmy.world 4 points 7 hours ago

Hey those cans have plastic liners so make sure you arent breathing in the smoke

[–] merc@sh.itjust.works 4 points 10 hours ago

Yep, it melts at something like 660C, so pretty low.

[–] Death_Equity@lemmy.world 101 points 16 hours ago* (last edited 16 hours ago) (4 children)

That is almost certainly aluminum, not enough lead in a modern car and the color is wrong.

Aluminum melts at a bit over 1200 degrees freedom, wildfires can exceed 2000 freedom units.

Engines, wheels, and suspension components are commonly made from aluminum. Looking at the scene presented, it is probably mostly the wheels that melted and ran downhill.

[–] GissaMittJobb@lemmy.ml 11 points 9 hours ago (1 children)

1200 F ~ 649 C

2000 F ~ 1093 C

[–] SmackemWittadic@lemmy.world 3 points 6 hours ago

Something about this really makes me want to see if you can separate out the component metals of a car via extremely high temp fractional distilation.

[–] thefartographer@lemm.ee 19 points 16 hours ago* (last edited 15 hours ago) (2 children)

Damn, you replied before I did. I was gonna say that it looks like someone is using leaded fuel

Edit: Also, the F does stand for freedom, so "degrees freedom" is correct. But I thought "freedom units" are like when you say how many infant-fevers hot a fire is.

[–] Death_Equity@lemmy.world 1 points 3 minutes ago

Units of freedom is a measurement of freedom related to the number of children killed in school shootings.

Freedom units are units of measurement in countries that have been to the moon, analogous to saying metric in referring to a base 10 measurement system that was used to get to the moon.

[–] Tolookah@discuss.tchncs.de 14 points 15 hours ago (1 children)

Today was a cold, stiff day with only 3 degrees of freedom

[–] ArtVandelay@lemmy.world 6 points 11 hours ago

with only 3 degrees of freedom

So almost fully constrained!

[–] seathru@lemmy.sdf.org 13 points 16 hours ago* (last edited 15 hours ago) (1 children)

Magnesium alloy subframe, suspension, and wheels are also fairly common in modern cars.

[–] fahfahfahfah@lemmy.billiam.net 20 points 15 hours ago

FWIW the magnesium would burn rather than melt probably

[–] Transcendant@lemmy.world 46 points 14 hours ago (1 children)

Clearly what we're seeing here is the T1000. I highly recommend running away before it reforms.

[–] MeatPilot@lemmy.world 12 points 14 hours ago (2 children)
[–] sbv@sh.itjust.works 6 points 12 hours ago

Wolfie's fine, dear. Wolfie's just fine. Where are you?

[–] jrwperformance@lemmy.world 16 points 15 hours ago (1 children)

Looks like a newish BMW 5 series. The puddles of metal are a mix of aluminum and magnesium. BMW uses a lot of magnesium in the engine block and other parts.

[–] grue@lemmy.world 2 points 11 hours ago (1 children)

Wouldn't the magnesium burn instead of melt, though?

[–] piecat@lemmy.world 3 points 11 hours ago (1 children)

Probably not enough surface area. Magnesium alloys are mostly dangerous when you're metalworking. Dust, shavings, turnings, that's a real hazard.

[–] grue@lemmy.world 4 points 10 hours ago* (last edited 10 hours ago)

I mean, it's true that solid (not powdered) magnesium is safe to use because it's not going to spontaneously burst into flames on its own from high temperatures alone, but that's not what we're talking about. We're talking about what happens to it after the car is already fully engulfed in flames from another source. I've been doing some reading about it in the last 10 minutes, and the sources I've found have pretty much been in agreement that when exposed to flame, the temperature at which the magnesium would combust is lower than the one at which it would melt.

For example, from https://firefighterinsider.com/magnesium-flammable/ :

Magnesium... will ignite at temperatures of around 630 degrees Celsius or 1166 degrees Fahrenheit.

...

Magnesium melts at about 1,202 degrees Fahrenheit or 650 degrees Celsius.

In most cases, it will ignite before it melts and molten magnesium is something that would need to be made under strict conditions in a lab.

My guess is that the re-solidified pool of metal is probably close to 100% aluminum or maybe a mix of aluminum and steel, but wouldn't contain much magnesium. (Or rather, the magnesium it would contain would be particles of MgO (magnesium ash) suspended in it, not metallic Mg.)

I suppose if we're talking about aluminum-magnesium alloy car parts instead of pure magnesium ones, the eutectic nature of the alloy might cause the pieces to melt before they caught on fire. But once it is melted, I'm not sure being mixed with aluminum would continue to stop the magnesium from igniting.

See also:

[–] jewbacca117@lemmy.world 21 points 16 hours ago

It's aluminum. There's a number of places in the engine it could have come from. Have some friends that kept similar souvenirs after losing cars in the Camp Fire.

[–] Kaput@lemmy.world 17 points 15 hours ago (1 children)

Looks like a fallout screenshot. It you pan just a little to the right there would be the red rocket gas station and dogmeat looking at you.

[–] kabi@lemm.ee 3 points 12 hours ago

From the corner of my eye, I thought it was exactly that.